Wire bonding means

ABSTRACT

Apparatus of improved construction for bonding a wire to several locations on one or more workpieces wherein a slide member having a tool mounted thereon is movable along a generally vertical path into and out of a number of operative positions under the influence of rotatable cam means whose movement is transferred by a number of levers to the slide member. One of the levers is constructed to provide a &#39;&#39;&#39;&#39;knee-action&#39;&#39;&#39;&#39; effect to assure that the lever will remain in engagement with an adjustable abutment surface associated with a particular cam to eliminate vibration of the slide member as it moves between certain of the operative positions thereof. A wire cutting and pulling unit operates to cut the wire after the last bond and to separate the excess wire projecting from such bond.

United States Patent [1 1 Diepeveen 51 Jan. 9, 1973 [54] WIRE BONDING MEANS 22 Filed: April 14, 1971 211 Appl.No.:133,932

Primary Examiner.lohn F. Campbell Assistant ExaminerR. J. Craig Attorney-Townsend & Townsend [57] ABSTRACT Apparatus of improved construction for bonding a wire to several locations on one or more workpieces wherein a slide member having a tool mounted thereon is movable along a generally vertical path into and out of a number of operative positions under the influence of rotatable cam means whose movement is transferred by a number of levers to the slide member. One of the levers is constructed to provide a kneeaction" effect to assure that the lever will remain in engagement with an adjustable abutment surface associated with a particular cam to eliminate vibration of the slide member as it moves between certain of the operative positions thereof. A wire cutting and pulling unit operates to cut the wire after the last bond and to separate the excess wire projecting from such bond.

22 Claims, 19 Drawing Figures PATENTED JAN 9 I975 SHEET DlUF 12 JOHN C. D/EPEVEEN INVENTOR.

PATENTEU JAN 9 I975 SHEET U30F 12 w@ M R i n 0 v -I IHO# n mm "I I l w l L 1 moT I BY I lownsend b'lownsend PATEN TED JAN 9 I973 SHEET UQUF 12 JOHN c. D/EPE VEEN FIG. 4

INVENTOR.

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PATENIEUJAN 9 ma 3.709422 SHEET UBUF 12 JOHN c. DIEPE VEEN IN VE N TOR lownsend i loumsend PATENTEDJAN 9 ma SHEET [NW 12 JOHN C. D/EPEVEEN INVENTOR.

lownsend loLunsend PATENTEDJAN 9 I975 SHEET U8UF 12 JOHN C. D/EPEVEEN INVENTOR.

'loumsend PATENTED JAN 9 I975 SHEET 10 0F 12 INVE N TOR.

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m NMN JOHN C. DIEPEVEEN Mme ATTORNEYS Pmminm 197s 3.709.422 SHEET 1 2 HF 12 F I G. l 9 302 5|0 5:2 T0 TOOL 74 I INVENTOR.

- JOHN C. DIEPEVEEN v ATTORNEYS WIRE BONDING MEANS This invention relates to improvements in wire bonding machines and, more particularly, to an improved wire bonding apparatus having a vertically movable, tool-carrying slide member.

The present invention provides certain improvements in a wire bonding machine of the type utilizing the teachings set forth in U. S. patent application Ser. No. 18,153, filed Mar. 10, 1970, now U.S. Pat. No. 3,653,268, entitled TOOL MOVING MECHANISM". In this disclosure, a vertically mova ble slide member having a tool mount shiftably carried thereby is movable into a number of operative positions, starting from a home position to a first search position, an intermediate search position, a second search position and back to the home position. In the first and second search positions, the tool mount is shifted relative to the slide member so that the tool can be moved into and out of a bond position at which it bonds a wire to a workpiece, such as an integrated circuit chip or a terminal or post associated therewith.

Cam means is provided with several lever assemblies to cause movement of the slide member and the tool mount. One of these levers is disposed to engage an abutment surface whose inclination can be varied to vary the location of the slide member when the latter is in, the corresponding search position. This one lever has associated with it a rigid arm which causes the lever to move away from and be spaced relative to the abutment surface before the slide member moves into the corresponding search position. Thus, when the slide member does, in fact, move into such search position, the lever moves toward the abutment surface and strikes the same, causing vibrations to be transmitted to the slide member. These vibrations are to be clearly avoided because they are oftentimes transmitted to the tool. Thus, the tool, upon vibrating, can possibly engage the workpiece and damage the same even though the tool has not yet moved into the bond position.

An improvement of the present invention which operates to avoid this problem is the replacement of the rigid arm mentioned above with a pair of relatively shiftable arms which provide a knee-action effect for the aforesaid one lever so that the lever does not move out of engagement with its abutment surface prior to the movement of the slide member into the corresponding search position. Thus, as the slide member moves into such search position, the one lever is already in the proper position, engagingthe abutment surface, and disposed to permit immediate adjustment of the search position of the slide member by changing the inclination of the abutment surface itself. In effect, therefore, the relatively shiftable arms providing the knee-action" effect operate as a rigid, unitary arm when the slide member is in the corresponding search position but operate as two pivotally interconnected, angularly disposed arms when the slidemember is in other positions.

Another improvement utilized with the tool mechanism of this invention is the provision of a wire handling unit which includes means for cutting the wire after the last bond is made by a tool and then pulling any excess wire projecting from the last bond to separate such excess wire and thereby eliminate problems associated therewith. Wire cutting means and a wire clamp are carried together on a shiftable arm which moves sequentially toward the tool after the last bond and the cutting. means cuts the wire and the wire clamp moves onto the "wire extension projecting from the last bond. The wire clamp has jaws which move first in a generally horizontal plane with the cuttingmeans and then along a path transverse to such planealong the length of the excess wire before the jaws are clamped onto the same. After being clamped on the ex cess wire, the jaws move in reverse along the transverse path to, in fact, lift the excess wire from the bond to eliminate interference with adjacent wires. Then, the wire clamp and the cutting means are moved once again in the generally horizontal plane but away from the tool while the jaws remain clamped onto the excess wire. When the jaws open at a location remote from the tool, the excess wire can be collected in an accumulator by suction or other means.

The primary object of this invention is to provide im provements in wire bonding machines of the type utilizing a vertical movable tool mount wherein vibrations of the tool mount are minimized or eliminated before or during a bonding operation to avoid damage to the workpiece and excess'wire can be removed from the workpiece after a bonding operation.

Another object of this invention is to provide an improved wire bonding machine of the type described wherein the machine has cam drive means whose motion is transmitted by an improved lever tothe tool mount for moving the latter, with the lever providing a knee-action" effect to permit the lever to remain in an operative condition before and as the tool mount moves into a search position to thereby eliminate the build-up of vibrations which would otherwise occur if the lever were to move into such operative condition as the tool mount moves into the search position.

Still a further object of this invention is to provide a machine of the aforesaid character having an improved wire handling unit which cooperates with themeans for moving the tool mount to sequentially remove excess wire from a workpiece after thelast bond by the tool on the tool mount to provide substantially automatic, highly efficient operation of the machine.

Other objects of this invention will become apparent as the following. specification progresses, reference being had to theaccompanying.drawings for an illustra tion of the invention.

In the drawings:

FIG. 1 is afront elevational view of a mechanism for movingatoolinto aunumber of operative positions;

FIG. 2 is atop planview of the mechanism of FIG. 1;

FIG. 3 is a cross-sectional view of a portion of the mechanism, showingthe tool in a first operative position;

FIG. 4 is a fragmentary, cross-sectional view of another portion of the mechanism, parts being broken away to illustrate details of construction;

FIG. Sis a view similartoFIG. 4 but showing the mechanism for another operative condition;

FIG. 6 is a fragmentary, sideelevational view of the mechanismlooking fromthe leftwith respect to FIGS. 1 and 2;.

FIGS; 7 and 8 are-schematic. views of portions of the mechanism, illustratingvthe movement of the tool from a search position to a bond position;

FIGS. 9-12 are schematic views of portions of the mechanism illustrating the sequence of steps required to move the tool into various operative positions;

FIG. 13 is a graphic view of the operative positions of the cams utilized to drive the tool into its various operative positions;

FIG. 14 is a top plan view of the wire handling unit for cutting the wire and removing'excess wire from a workpiece;

FIG. 15 is a front elevational view of the wire handling unit of FIG. 14;

FIG. 16 is a fragmentary, side elevational view of the wire handling unit in a first operative location; and

FIG. 17 is a view similar to FIG. 16 but showing the unit in another operative location; and

FIGS. 18 and 19 are side and front elevational views, respectively, of an improved wire drag unit.

The tool translation mechanism of the wire bonding machine of this invention is broadly denoted by the numeral l and includes a base plate 12 to the front end of which a pair of generally vertically disposed, parallel first side plates 14 and 16 is rigidly secured. The first side plates extend forwardly from the front end face 18 of base plate 12 (FIG. 6). A pair of second side plates 20 and 22 are rigidly secured to the sides of base plate 12 and extend upwardly therefrom in parallelism with first side plates 14 and 16.

First side plates 14 and 16 are adapted to mount a vertically sliding member 24 thereon by means ofa pair of side bearings broadly denoted by the numerals 26 and 28, respectively, (FIG. 1). Member 24 has an opening 30 therethrough (FIG. 3) near the upper end thereof for receiving an arm 32 rigidly mounted on a first, generally horizontal upper shaft 34 (FIG. 2) spanning the distance between first side plates 14 and 16. The outer end of arm 32 is adapted to engage the lower end of a screw 36 threaded into the upper portion 38 of slide member 24. Screw 36 provides an adjustment means for raising and lowering slide member 24 relative to arm 32.

A reciprocal rod 40 is shiftably carried in a generally horizontal sleeve 42 rigid to and extending through slide member 24 below opening 30 as shown in FIG. 3. The outer end of rod 40 (the left-hand end of the rod when viewing FIG. 3) bears against a pin 44 projecting laterally from the lower end of a first bar 46 pivotally mounted at its upper end by a pin 48 on an upper pair of spaced, lateral projections 50 and 52 (FIG. 2) which are rigid to and extend forwardly from upper portion 38 of slide member 24. A coil spring 54 (FIG. 3) interconnects member 24 and first bar 46 to bias the bar in a counterclockwise sense when viewing FIG. 3, spring 54 being connected to one end to a pin 56 in an opening 57 extending through member 24 and at the other end to a pin 59 (FIG. 2) on projection 50.

A second pivotal bar 58 is hingedly mounted by a pin 60 (FIG. 3) on a lower pair of spaced, lateral projections 62 and 64 (FIG. 1) for pivoting movement about a generally horizontal axis parallel to the axis of pin 48. Bar 46 has an adjustable screw 65 provided with a conical or convex tip or point 66 (FIG. 3) which normally engages the outer face 68 of bar 58 to lock the latter against movement relative to slide member 24. An adjustable screw 67 is threadably mounted on bar 58 below screw 65 and has a conical or convex tip or point 69 which normally engages the front face of slide member 24.

A tool mounting member or arm 70 is rigidly secured to bar 58 and projects forwardly therefrom as shown in FIG. 3. Member 70 is adapted to mount a wire bonding tool 72 of conventional construction, the tool having a capillary therethrough for feeding a wire 74 to be bonded to a workpiece, such as an integrated circuit chip or to a post associated with the chip. By virtue of the aforesaid construction, arm 70 is releasably secured to slide member 24.

A rod 76 is rigid to and extends forwardly from bar 46. A coil spring is secured at one end thereof by an adjustable sleeve 78 to rod 76 and at the opposite end thereof to member 70 near bar 58 as shown in FIG. 3. Spring 80 is normally under tension to bias tool 72 downwardly or in a counterclockwise sense when viewing FIG. 3. By properly selecting the tension of the spring, the tool will exert a predetermined force to the bead on the lower end of wire 74 to urge the bed into engagement with a workpiece.

Insofar as it is described, mechanism 10 operates to cause too] 72 to move into proximity with a location to which wire 74 is to be bonded. To this end, assuming member 24 has been lowered to the proper position, rod 40 is moved to the left when viewing FIG. 5. Thus pivoting bar 46 in a clockwise sense about pin 48, thereby moving tips 66 and 69 of bars 46 and 58, respectively, to the left whereby bar 58 pivots in a counterclockwise sense around pin 60 due to the unbalanced force thereon caused by the difference between the weight of member 70 and the counterforces caused by weight 78 and the tension of spring 80. Thus, the tool 72 is lowered into proximity to the workpiece and forces the wire against the same. Heat is applied to the wire to bond the same to the workpiece. Although bar 58 pivots about pin 60, the movement of the tool is essentially straight-line movement since the distance through which the tool moves is quite small, of the order of only several mils at most. The tension of spring 80 and weight 78 operates to determine the force with which the tool is applied to the wire to force the wire against the location to be bonded. FIGS. 7 and 8 schematically illustrate the relative locations of the two pivotal bars 46 and 58 before and during the bonding step, FIG. 7 showing the tool in a search position and FIG. 8 showing the tool in the bond position. Return of bars 46 and 58 to the positions of FIGS. 3 and 7 caused tool 72 to elevate to its initial condition and tips 66 and 69 move back into engagement with bar 58 and slide member 24, respectively. Screws 6S and 67 serve to lock bars 46 and 58 against movement when such bars are in the positions of FIGS. 3 and 7; thus, tool 72 is rigidly connected to slide member 24 except when the tool is moving to and from its bond position.

A coil spring 82 (FIGS. 1 and 6) is coupled at one end thereof to a pin 84 on a lower end of first side member 14 and at the opposite end to a second pin 86 projecting laterally from slide member 24. Thus, the slide member is biased downwardly by spring 82 but its downward movement is controlled by the operative position of arm 32.

Slide member 24 has the following operative positions: the home position at which the tool is at its highest point; the first search position at which the tool is adjacent to but spaced above a first surface to which a first end of the wire is to be bonded; an intermediate search position above the first search position; and a second search position below the intermediate search position and either above or below the first search position depending upon whether a second surface to which the second end of the wire is to be bonded is above or below the first surface. When slide member 24 is in either of the first or second search positions, rod 40 is moved to pivot bars 46 and 58 to thereby cause lowering of tool 72 into the bond position. The movementof the slide member 24 is as follows: initially, it is in the home position, then it is moved to the first search position and remains there until tool 72 is moved into and out of its bond position. Then, member 24 moves upwardly to the intermediate search position, then downwardly to the second search position at which it remains until tool 72 is again moved into and out of its bond position. Then member 24 returns to the home position. The location of the slide member when it is in any one of the first search, intermediate search and second search positions can be adjusted in a manner to be described. Also, the time during which the tool is in its bond position can be selected to assure a proper bond without applying excess heat to the workpiece.

The means for effecting the movement of slide member 24 and rod 40 includes a number of spaced cams (FIGS. 1 and 2) rigidly mounted on a shaft 88 which is rotatably mounted on and spans the distance between second side members and 22 as shown in FIGS. 1 and 2. One end of shaft 88 has a pulley 90 which is coupled by a timing belt 92 to a second pulley 94 on the drive shaft 96 of a motor 98 which is sequentially actuated in a manner to cause the slide member 24 to move into its various positions for a single revolution of shaft 88. The rate at which motor 98 is actuated can be varied to, in turn, vary the rate at which member 24 is moved into its operative positions.

The cams include a first cam 100 for controlling the intermediate search position of the slide member, a second cam 102 for controlling the home position of the slide member, a third cam 104 for controlling the movement of rod 40, and a fourth cam 106 for controlling the second search position of the slide member. The first search position of the slide member is adjusted by means of screw 36 which, when manipulated, raises or lowers slide member 24 with respect to arm 32 (FIG. 3). This is to be done only when slide member 24 is in the first search position. In this way, tool 72 can be adjusted in height with respect to the workpiece before the tool makes the first bond.

In addition to the foregoing cams, spaced timing cams 108, 110, 112 and 114 are also rigidly secured to shaft 88 and are coupled with respective electrical switches 115, 116, 118 and 120, the switches secured in any suitable manner adjacent to respective timing cams, such as by rod-like supports 122 secured to and spanning the distance between second side plates 20 and 22. Switch 115 controls the bond time, switch 116 controls the operation of motor 98, switch 118 controls the operation of a wire-cutting torch, and switch 120 is a stitch switch.

A second shaft 124 (FIGS. 1 and 2) is rotatably mounted on and spans the distance between first side members 14 and 16 directly below and parallel with shaft 34. A first crank arm 126 (FIG. 6) is coupled to one end of shaft 124 adjacent to first side plates 14 and 16 and extends upwardly therefrom. The upper end of crank arm 124 is pivotally coupled to one end of a lever 128. The opposite end of lever 128 has a first roller 130 in engagement with the outer cam surface of cam (FIG. 1). A second roller 132 of the same size as roller and coaxial therewith is disposed to engage the fiat surface 134 (FIG. 6) ofa crescent shaped member 136 mounted on the inner end of a cylindrical bearing 138 rotatably mounted within and extending through second side plate 20 (FIGS. 1, 2 and 6). An adjustment rod 140 rigid to bearing 138 extends forwardly therefrom and provides a means for manually rotating bearing 138 and thereby member 136.

Flat surface 134 of member 136 is radially spaced from the central axis of bearing 138 (FIGS. 9-12). A coil spring 142 secured at its ends to pins 144 and 146 (FIGS. 2 and 6) on second side plate 20 and lever 128, respectively, biases roller 130 into engagement with cam 100. Thus, as cam 100 moves roller 130 with respect to shaft 88, roller 132, if it engages surface 134, is shifted along such surface and, depending upon the angularity of this surface, crank arm 126 is caused to pivot about the axis of shaft 124. For instance, if roller 132 is moved downwardly by the rotation of cam 100 and if surface 134 is inclined as shown in FIGS. 9-12, lever 128 must move to the right when viewing FIG. 6 to, inturn, cause pivotal movement of arm 1 26 in a clockwise direction. Since arm 126 is rigid to shaft 124, the shaft is also rotated in a clockwise sense. The purpose of the rotation of shaft 124 will be set forth hereinafter. Thus, crank arm 126 and lever 128 define a first levermeans for rotating shaft 124 in response to the rotation of shaft 88 g A second crank arm 146 (FIGS. 2, 3 and 6) is rigidly secured atone end thereof to shaft 124 between first side plates 14 and 16. Arm 146 extends upwardly from shaft 124 (FIG. 3) and has a roller 148 on its upper end thereof for engaging the outer peripheral cam surface of cam 102. Thus, as arm 146 is pivoted by the rotation of cam 102, it rotates shaft 124.

Means for moving rod 40 to the leftwhen viewing FIG. 3 includes a follower 150 having a flat surface 152 which normally engages the convex rear face of rod 140 as shown in FIG. 3. Follower 150 is rigidly secured in any suitable manner to an arm 154 which. is pivotally mounted at one end thereof on shaft 34 and has a roller 156 on the opposite end thereof. Roller 156 normally engages the outer peripheral cam surface of cam 104, the latter having a pair of spaced lobes (FIGS. 7 and 8) thereon which, when cam 104 is rotated, cause arm 154 to successively pivot about shaft 134 in a clockwise sense when viewing FIG. 3. Each time this occurs, follower 150 forces rod 40 to the left when viewing FIG. 3 to, in turn, pivot bar 46 about pin 48, allowing bar 58 to pivot about pin 60 to cause a lowering of tool 72 into its bond position. Spring 54causes return of rod 40 to its initial position when either lobe of the cam 104 moves past roller 156.

A third crank arm 158 (FIGS. 1, 2, 4 and 5) is rigidly secured at one end thereof to shaft 124 adjacent to first side plate 16, i.e., at the end of shaft 124 opposite to first crank arm 126. Arm 158 is shown displaced to the left in each of FIGS. 4 and 5 merely for the sake of clarity. Arm 158 extends upwardly from shaft 124 and has a short pin 160 projecting toward first side plate 16. Pin 160 is disposed to engage a flat surface 162 on the upper extremity of a connector arm 164, the latter being pivotally mounted at two locations. Firstly, it is pivotally connected intermediate its ends by a pin 166 to the lower end of an adjacent arm 168. Secondly, it is pivotally connected at its lower end by a pin 170 to the front end of a lever 172 which extends rearwardly of arm 164 as shown in FIGS. 4 and 5. The upper end of arm 168 is rigidly secured to shaft 34 and causes rotation of the same each time arm 164 is pivoted with respect to the adjacent first side plate 16.

Arm 164 is caused to pivot in two different ways. In the first way, the counterclockwise movement of third crank arm 158 when viewing FIGS. 4 and 5 causes pin 160 to urge arm 164 in a counterclockwise sense about pin 170. This causes arm 168 and thereby shaft 34 to rotate in a clockwise sense (FIG. 4). Since arm 32 is rigidly secured to shaft 34, arm 32 is pivoted in a clockwise sense when viewing FIG. 3 about the axis of shaft 34 to cause elevation of slide member 24. Thus, slide member 24 is elevated each time crank arm 158 is caused to rotate in a counterclockwise sense when viewing FIGS. 4 and 5. This occurs when intermediate search cam 100 causes roller 132 to move downwardly along surface 134, to, in turn, cause lever 128 to move to the right (viewing FIG. 6) to cause clockwise rotation of shaft 124 (viewing FIG. 6).

When slide member 24 is in the intermediate search position, adjustment of this position can be accomplished by rotating bearing 138 by raising or lowering rod 140. This causes a change in the inclination of surface 134 and, in essence, causes lever 128 to move forwardly or rearwardly depending upon the direction of rotation of the bearing. This is because roller 132 is radially displaced from the axis of bearing 138 (FIG. 11) so that a change in the inclination of surface 134 will cause movement of roller 132 either to the right or to the left when viewing FIG. 11. Adjustment of the position of slide member 24 in this manner determines the loop height of the wire after the first bond.

Lever 172 has a pair of rollers 174 and 176 on the rear end thereof, the rollers being of essentially the same size and coaxial with each other. Roller 174 normally engages the outer peripheral cam surface of cam 106 and roller 176 is disposed for engaging the flat surface 178 of a crescent-shaped member 180 rigid to the inner end of a cylindrical bearing I82. Bearing 182 is coaxial with bearing 138 and is rotatably mounted in second side plate 22. An adjustment rod 184 is secured to and extends forwardly from bearing 182 to permit manual adjustment of the inclination of surface 178. A coil spring 186 (FIGS. 4 and 5) biases roller 174 into engagement with the cam surface of cam 106, one end of spring 186 being coupled to a pin 188 on the inner surface of second side plate 22 and the opposite end of the spring being coupled to a pin 190 on lever 172.

A second way in which arm 164 is caused to pivot relative to pin 170 is through the action of cam 106 which causes roller 176 to move along surface 178 of crescent-shaped member 180 depending upon the position of the cam and the inclination of surface 178. As roller 176 moves downwardly by cam 106, lever 172 is moved to the left when viewing FIGS. 4 and 5, causing pin and thereby pin 166 to move in a clockwise sense about the axis of shaft 34. This, in turn, causes shaft 34 to pivot in a clockwise sense, whereby arm 32 elevates slide member 24. In the alternative, reversing the inclination of surface 178 and causing roller 176 to move along the same will cause lever 172 to move to the right, whereby arm 32 permits slide member 24 to descend. Thus, by raising or lowering rod 184 to change the inclination of surface 178, the second search position of slide member 24 can be adjusted with respect to first side plates 14 and 16.

Mechanism 10 is adapted to be confined within a housing (not shown) so as to protect the various moving parts thereof. The mechanism is to be used with a combination wire cutter and pulling unit of the type shown in FIGS. 14-17 so that wire 74, after being bonded two or more times by tool 72, can be cut after the last bond and the excess portion of the wire extending from the last bond can be removed therefrom. The reason for this is that the wire is generally carried by the machine in the form of a spool and is advanced incrementally through the capillary of tool 72 as it is needed. Moreover, when the wire is cut, it is necessary to form a bead of the proper size on the lower end of the wire before the wire is moved into engagement with the first bond location. The wire cutting and pulling unit to be described not only effectively cuts the wire and separates the excess portion from the second bond, but it also assures that a head of uniform size will be formed at the lower end of the wire at the time the wire is cut so that the desired bond can be made when the wire is next moved to the first bond location.

Unit 200 includes a wire cutting torch 202 and a wire clamp 204, both of which are carried by an arm 206 for swinging movement in a generally horizontal plane with respect to tool 72. Arm 206 is pivotally mounted by a pin 208 on a projection 210 extending late rally from a member 212 secured to the lower end of a generally vertical shaft 214 which is mounted for rotation relative to tool 72 by a pair of vertically spaced bearings 216 and 218 secured to a plate 220, the latter being secured in any suitable manner to a support 222 attached to or forming a part of the housing in which mechanism 10 is disposed. Shaft 214 has a nut 222 threaded on the upper end thereof to permit vertical adjustment of shaft 214. An L-shaped lever 224 rigidly secured to shaft 214 between bearings 216 and 218 thereof has a screw 226 which serves as a stop and engages one face 228 of plate 220 after arm 206 has moved through a predetermined arc in a counterclockwise sense when viewing FIG. 14. Arm 206 can still rotate through a small arc relative to plate 220 after screw 226 has engaged face 228 because arm 206 is pivotally mounted by pin 208 on projection 210.

A first rod 230 is secured to and extends outwardly from member 212 as shown in FIG. 15. A bracket 232 shiftably mounts rod 230 and holds torch 202 in place with the tip 234 of the torch in proximity to and slightly above the forward extremity of wire clamp 204 (FIG. 16). A second rod 236 is parallel to and below rod 230 and shiftably extends through member 212 (FIG. 15). One end of rod 36 is rigidly secured to bracket 232 and the opposite end of rod 236 has a nut 238 threaded thereon, whereby the location of bracket 232 along the length of rod 230 can be adjusted. A coil spring 240 surrounding rod 236 operates to bias bracket 232 away from member 212.

Wire clamp 204 includes a pair of relatively shiftable jaws 242 and 244, jaw 242 being rigidly secured to a mounting plate 246 and jaw 244 being pivotally mounted intermediate its ends by a pin 248 on plate 246. A solenoid 250 carried by a bracket 252 at one side of plate 246 has a drive shaft 254 secured to the rear end 256 ofjaw 244. The front ends 258 and 260 of jaws 242 and 244, respectively, clamp a wire extension therebetween when the solenoid 250 is energized.

Mounting plate 246 is pivotally mounted on a pin 262 carried by a bracket 264 rigid to and extending laterally from the outer end of rod 230. Mounting plate 246 has a slot 266 at the rear thereof for receiving the front end of an inclined arm 268, the latter being pivotally mounted by a pin 270 on mounting plate 246. The rear end of arm 268 is pivotally mounted on a pin 272 rigid to and extending outwardly from the outer end of arm 206. The connection between arm 206 and mounting plate 246 through arm 268 permits mounting plate 246 to pivot about pin 262 relative to bracket 264 as arm 206 continues to move through the aforesaid small are after screw 226 has engaged face 228. Thus, after torch 202 has come to a halt after being moved about the axis of shaft 214, continued movement of arm 206 about the axis of pin 208 causes jaws 242 and 244 to pivot together downwardly through a limited distance. A coil spring 274 is under tension and spans the distance between arm 206 and pin 262 as shown in FIG. 14.

Essentially, the movement ofjaws ends 258 and 260 will be straight-line movement although plate 246 does, in fact, pivot about pin 262. The reason for this is that the distance of travel of the jaws is not so great as to have any appreciable rotational effect.

Means for reciprocating arm 206 includes a rod 276 coupled at one end thereof to arm 206 and to the opposite end thereof to a reciprocal rod drive means shown schematically in FIG. 14 and denoted by the numeral 278. Drive means 278 is sequentially actuated after the second or last bond of a wire has been made. When this occurs, rod 276 causes arm 206 and rod 230 to move together toward wire 74 and about the axis of shaft 214 until screw 226 engages face 228 of plate 220. Either before or at the time this occurs, the flame of the torch cuts the wire to form a wire extension 282 projecting upwardly from the last bond. Also, a bead of uniform size is formed on the lower end of the wire extending downwardly from too] 72.

When screw 226 engages face 228, rod 230 and thereby torch 202 are brought to a halt but arm 206 continues to rotate through the aforesaid small arc, causing mounting plate 246 to pivot in a clockwise sense, when viewing FIG. 16, about pin 262. This causes jaws 242 and 244 to move downwardly on op posite sides of the wire. When the downward movement of the jaws stops, solenoid 250 is energized, causingjaw 244 to move toward jaw 242 to clamp wire extension 282 therebetween. Immediately, the jaws are caused to elevate because rod 276 is immediately reversed. This causes arm 206 to pivot about the axis of jaws. Continued movement of rod 276 then causes arm 206 to move with rod 230 as they return to their initial positions. When this occurs, the jaws, with extension 282 still clamped therebetween, move the wire extension to a location remote from the workpiece at which location solenoid 250 is deenergized, opening the jaws and allowing the wire extension to be released. Vacuum pickup means near the path of the wire clamp can be used to collect the wire extension. The tool is.

then ready to commence the bonding of the next wire.

OPERATION To illustrate the operation of the bonding machine of this invention, reference is first made to FIGS. 9-12, each of which shows the configuration of cams 100, 102, and 106 and the operating relationships between the cams and crank arms 126, 146 and 158. These elements operate to control the operative position of arm 32 and thereby the operative position of slide member 24. FIGS. 9, 10, 11 and 12 illustrate the relationships of these elements when slide member 24 is in the home position, the first search position, the intermediate search position, and the second search position, respectively.

In the home position (FIG. 9), cam 102 maintains crank 146 in a position such that arm 32 holds slide member 24 in a relatively high position and arm 158 is tilted as shown inFIG. 9, causingarm 164 to be in an inclined position. Also, roller 176 is in engagement with surface 178 and the axis of roller 176 is substantially coaxial with the axis of bearing 182.

As shaft 88 is rotated under the influence of drive motor 98, cam 102 rotates in a clockwise sense when viewing FIGS. 9 and 10 and the lobe of this cam moves past roller 148 of crank arm 146, causing shaft 124 to rotate in a clockwise sensefwhen iviewingFIGSA and 5 causing the following to occuri crank arm 1 58 rnoves in a clockwise sense (FIGS. 4 5f).'andypi nilfifi; allows arm 164 to return from the inclined posit'io of'FIQA to the generally uprightpositionlofFl of arm 164 causes movement'of pin 166'in a clockwise sense about pin 170 to, in turn, cause rotation of shaft 34 in a counterclockwise sense (FIG. 4), and arm 32 thereby rotates in a clockwise sense (FIGS. 9 and 10) to permit lowering slide member 24 into the first search position. In this position, roller 176 on lever 172 is still in engagement with surface 178 of crescent-shaped member 180 and is also coaxially aligned with the axis of bearing 182. Also, theposition of pin 170 remains unchanged except for a small downward movement and arms 164 and 168 effectively form a single, rigid unitary arm since pin 160 is now coaxial with shaft 34 and pin 160 moves arm 164 until surface 162 engages shaft 34 as shown in FIG. 5. Surface 162 approaches and moves into engagement with shaft 34 in a sinusoidal manner, i.e., at a relatively high speed during the major portion of its movement and at a relatively low speed approaching zero speed as it nears shaft 34. This is due to the continuous, outer peripheral cam surface of cam 102. Also, in the first search position (FIG. 10), crank arm 126 becomes generally upright due to .s. movement the rotation of shaft 124 and roller 132 moves into engagement with surface 134 of crescent-shaped member 136. Also, roller 132 moves into coaxial alignment with bearing 138. Because of the coaxial alignment of rollers 132 and 176 with respective bearings 138 and 182, rotating of such bearings has no effect on the positions of respective levers 128 and 172. However, the first search position is adjusted by manipulating screw 36.

In the first search position, the rotation of shaft 88 is usually stopped by interrupting the operation of drive motor 98, so that the first search position can be adjusted or to permit manipulation of the workpiece relative to tool 72. Movement of screw 36 causes slide member 24 to be raised or lowered with respect to arm 32.

When member 24 is in the first search position, continued rotation of shaft 88 through a predetermined arc, such as about 62, will cause arm 70 with tool 72 to be released from a locked position and to be rotated about pin 60 so that the tool can move downwardly and into its bond position, following which it is raised to its locked position. This is illustrated in FIGS. 7 and 8, wherein FIG. 7 shows the relative positions of slide member 24 and tool 72 before one of the lobes of cam 104 rotates into engagement with roller 156 on arm 154. When this occurs, as shown in FIG. 8, follower 150 forces rod 40 to the right when viewing FIG. 8, pivoting bar 46 about pin 48 to, in turn, allow bar 58 to be released and to pivot about pin 60, causing tool 72 to descend. The tool, heated by an electrical heater carried thereby, then forces the bead on the lower end of the wire into engagement with a heated workpiece with a predetermined force determined by the tension of spring 80 and a eutectic weld is accomplished. The shape of the lobe of cam 104 is such that a sinusoidal motion is imparted to tool 72 when it is lowered and as the bead contacts the workpiece. An adjustable time delay unit forming part of a control means (not shown) deactuates motor 98 for a predetermined time interval when the tool is in the bond position (FIG. 8). At the expiration of such time interval, cam 104 is again rotated and, when the first lobe of the cam moves off roller 156, spring 54 returns bar 46 to its original position, causing tool 72 to elevate to the position shown in FIG. 7 and causing bar 46 to lock bar 58 against slide member 24. Thus, tool 72 is once again rigidly connected to slide member 24.

Continued rotation of shaft 88 causes the three crank arms 126, 146 and 158 to move into the operative positions of FIG. 11 corresponding to the intermediate search position of slide member 24. In such position, slide member 24 is elevated above the first search position because the single lobe of cam 100 moves into engagement with roller 132 as the latter is in engagement with flat surface 134 of crescent-shaped member 136, causing the roller to move downwardly along surface 134. This movement causes crank shaft 126 to pivot in a clockwise sense when viewing FIG. 11 to, in turn, cause arm 158 also to pivot in this direction. Movement of arm 158 causes pin 160 to urge arm 164 to an inclined position in a counterclockwise sense about pin 170 when viewing FIG. 4. This movement of arm 164 also causes arm 168 to pivot in a clockwise sense when viewing FIG. 4 to, in turn, cause rotation of shaft 34 in a clockwise sense when viewing FIG. 4, whereby arm 32 is moved upwardly and elevates slide member 24 into the intermediate search position. Also, the single lobe of cam 106 moves into engagement with roller 176, causing the latter to move downwardly along inclined surface 178 of crescent-shaped member 180, the inclination of surface 178 being adjustable so that the axis of roller 176 is no longer coaxial with that of bearing 182. Thus, the position of pin 170 is changed since it has moved to the right when viewing FIG. 11.

The knee-action effect of arms l64 and 168 permits roller 176 to remain in engagement with surface 178 as slide member 24 moves from the first search position (FIG. 10) to the intermediate search position (FIG. 11). Thus, when the slide member moves from the intermediate search position to the second search position, roller 176 will not bang into surface 178 so as to cause undesirable vibrations as would occur if a rigid arm were used instead of arms 164 and 168.

In the intermediate search position of slide member 24, drive motor 98 is stopped so that either the inclination of surface 134 of crescent-shaped member 136 can be varied to change the position of slide member 24 or the position of the workpiece relative to tool 72 can be changed, if desired. This position determines the loop height of the wire. When the tool is raised or lowered with respect to the workpiece as member 136 is rotated, roller 132 remains in engagement with surface 134 due to the bias force of spring 82 (FIG. 1

Continued rotation of shaft 88 causes the single lobe of cam to move off roller 132 in the sinusoidal manner described above so that crank arm 126 returns to its generally upright position shown in FIG. 12, thereby rotating shaft 124 in a counterclockwise sense (viewing FIG. 12), pivoting arm 158 sufficiently to allow engagement of surface 162 of arm 164 with shaft 34, the movement of arm 158 being in a sinusoidal manner. Thus, shaft 34 is rotated in a counterclockwise sense (viewing FIG. 5), causing arm 32 to lower slide member 24 into the second search position. It is to be especially noted, however, that roller 176 remains in the same position in FIG. 12 as it occupied in FIG. 11, namely, when slide member 24 was in the intermediate search position. In effect, therefore, the knee-action effect afforded by arms 164 and 168 permits lever 172 to be properly positioned for the second search condition before slide member 24 moves into the second search position, i.e., when the slide member is in the intermediate search position. Thus, there is no further movement of lever 172 when slide member 24 moves into the second search position and any vibration caused by a slamming" or banging" of roller 176 into engagement with surface 178 is clearly avoided. Hence, if arms 164 and 168 were replaced by a single arm, the single arm would be pivoted about shaft 34 in a clockwise sense (viewing FIG. 5) thereby pulling roller 176 away' from surface 178 as slide member 24 moves into the intermediate search position. Return of the single arm during movement into the second search position would cause roller 176 to slam" or bang into surface 178, causing vibrations to be transmitted to the slide member, resulting in the bouncing of the tool onto and off the workpiece and damage the same.

In the second search position, the inclination of surface 178 can be varied to, in turn, vary the operative position of arm 32 and thereby the operative position of slide member 24, i.e., the vertical distance between tool 72 and the workpiece. Adjustment can be made such that the second search position is either above or below the first search position. However, the second search position is at all times below the intermediate search position.

When the adjustment for the second search position has been made, the tool is moved into the bond position in the manner described above with reference to FIGS. 7 and 8 wherein tool 72 is released from its locked relationship to slide member 24 when bar 58 is allowed to pivot away from the slide member about pin 60. The aforesaid time delay unit again deactuates motor 98 for a predetermined time interval when tool 72 is in the bond position. At the expiration of such time interval, shaft 88 is again rotated by motor 98 to return the tool to its locked relationship with slide member 24. Also, cam 102 is rotated through an arc sufficient to cause the single lobe of this cam to engage roller 148 of arm 146 to, in turn, pivot arm 146 into the position of FIG. 9, causing slide member 24 to be elevated into the home position, at which time motor 98 is deactuated.

The foregoingsteps required to move the tool from the home position, to the first search position, to the first bond position, to the intermediate search position, to the second search position, to the second bond position and returned to the home position are all sequentially accomplished during a single revolution of shaft 88. This shaft is stopped and started in accordance with the aforesaid control means (not shown) which includes the aforesaid time delay unit.

Following the elevation of slide member 24 to the home position, the drive means coupled with rod 276 (FIG. 14) is actuated to cause rotation of arm 206 and rod 230 together in a generally horizontal plane in a clockwise sense when viewing FIG. 14 about the axis of shaft 214. Thus, the torch and wire clamp move together toward wire 74 until screw 226 approaches. and moves into engagement with side 228 of plate 220. When this occurs, the flame of the torch severs the wire into two parts (FIG. 16), one of which is wire extension 282, and arm 206 continues to rotate in the horizontal plane about the axis of pin 208 causing the jaws of the wire clamp to move downwardly and along wire extension 282. Solenoid 250 is energized when the jaws reach their lowermost positions, the jaws close and clamp onto wire extension 282, and the movement of rod 276 is reversed, whereupon the jaws separate wire extension 282 from the last bond (FIG. 17) and lift it therefrom. When the jaws are returned to theiruppermost positions, arm 206 continues to be moved in the aforesaid horizontal plane, moving the closed jaws away from the tool. At a certain distance from the tool, the solenoid is de-energized, opening the jaws and allowing release of wire extension 282. A suitable suction device (not shown) is disposed adjacent to the path of the wire clamp to draw the wire extension into an accumulator by suction. The machine is then ready to bond a second wire and, when actuated, shaft 88 is caused to rotate sequentially through another complete revolu tion as described above.

FIG. 13 illustrates graphically the functions of the various cams. Among the curves shown in FIG. 13 is curve 280 which represents the camming function of cam 102, also known as the homing cam. The plateau shown between and 290 indicates that portion of cam 102 which is adjacent to roller 148 of crank arm 146.

The action of cam 100, also known as the looping cam, is illustrated by curve 282 which has a single hump representing the single lobe on the cam. The lobe is effective in the range of to 220 in the single revolution of shaft 88.

Cam 104, the bond cam, operates as indicated by curve 284 which shows two humps corresponding to the two lobes oncam 104. The first bond position occurs during the time when shaft 88 rotates in .the range of 82 to 144 and the second bond occurs when the shaft 88 is in the range of 228 to 290.

Cam 106, the second search cam, has a characteristic curve 286 provided with a single hump representing the single lobe on the cam. The lobe is effective in the range of 144 to 346 of the rotation of shaft 88.

Curves 288, 290, 292 and 294 represent, respectively, the effective arcs of torch motor switch cam 115, the motor bond mechanism switch cam 116, the bond time switch earn 118, and the stitch switch cam 120.

A wire drag unit 300 is shown in FIGS. 18 and 19 and is adapted to be used with the wire bonding machine to apply a drag to the wire as it is being fed toward and into the capillary of tool 72. Wire drag unit 300 includes a pair of relatively shiftable jaws 302 and 304 mounted on the machine above the workpiece and to one side of the tool. Jaw 3041is rigidly secured to a plate-like extension 306 which, in turn, is rigidly securedtosupport 272 of the wirebontling machine. Screws308 connect jaw 304 to plate 306. Jaw 302 is pivotally mounted by a pin 310 on plate 306,-pin 310 being a generally horizontallydisposed. The two jaws have pads 312 between which wire 74 passes, thewire being movablealong a generally horizontal path as shown in FIG. 19 as it moves to the capillary of the tool. Pads 312 can be of a material suitable for cleaning the wire as it moves therebetween.

An L-shaped rod 314 is secured at one end thereof to the rear end of jaw 302 as shown in dashed lines in FIG.

18. A setscrew 316 releasably connects rod 314 to jaw An adjustable weight 318 ismou nted on the forwardlyextending portion 320 of rod 314. Weight 318 is forwardly of the vertical plane in which pin 310 is disposed. This biases jaw 302 toward jaw 304 in a counterclockwise sense when viewing FIG. 18. Thus, wire 74between pads 312 is providedl with a drag force which inhibits the movement thereof toward the tool. The wire emanates from a spool 322 on one side of unit 300.

By virtue of the foregoing construction, jaws 302 and 304 can be generally parallel witheach other and the drag force exerted on the wire can be adjusted by positioning the location of weight 318 on rod portion320, the latter generally being horizontally disposed and generally parallel with the jaws. A set screw 324 releasably connectsweight 318 to rod portion 320.

Iclaim:

1. In a wire bonding machine: a support; a slide member shiftablymounted onthe support formovement along a generally vertical pathya tool mount shiftably mounted on said slide member and movable 

1. In a wire bonding machine: a support; a slide member shiftably mounted on the support for movement along a generally vertical path; a tool mount shiftably mounted on said slide member and movable therewith, said tool mount adapted to carry a wire bonding tool thereon at a location permitting the tool to move a wire into bonding engagement with a workpiece; a first shaft mounted on the support for rotation relative thereto about an axis adjacent to said slide member; means coupling the first shaft with said slide member to cause sequential movement of the latter successively into a pair of operative positions along said path in response to the sequential rotation of the first shaft relative to said support; a second shaft rotatably mounted on the support; a pair of spaced cams rigidly secured to said second shaft, there being a cam for each of said operative positions, respectively; an abutment for each cam, respectively, each abutment being adjacent to the respective cam; a lever for each cam, respectively, each lever being disposed to simultaneously engage the respective cam and the respective abutment with each cam being operable to shift the respective lever relative to the support as the lever engages the respective abutment and with said second shaft through a predetermined arc, said cams being disposed to cause sequential movement of said levers as said shaft rotates relative to said support; knee-action means coupling said levers with said first shaft to cause sequential rotation of the latter in response to the sequential movement of said levers, whereby said slide member is successively moved into said operative positions, said knee-action means permitting one of the levers to remain in simultaneous engagement with the respective cam and the respective abutment when the slide member is in either of said operative positions; means coupled with the tool mount for shifting the same relative to said slide member when the latter is in a first of said operative positions, whereby a tool on said tool mount can be moved into a bond location for bonding a wire to a workpiece; means movable transversely of said path for removing excess wire from a workpiece after the tool has bonded the wire thereto; and means coupled with said second shaft for rotating the same.
 2. In a wire bonding machine as set forth in claim 1, wherein said knee-action means includes a pair of pivotally interconnected arms, one of the arms being pivotally coupled to said one lever and the other arm being rigidly secured to said first shaft.
 3. In a wire bonding machine as set forth in claim 1, wherein said knee-action means includes a pair of arms, one of said arms being rigidly coupled to and extending outwardly from said first shaft, the other arm being pivotally mounted on the outer end of said one arm and projecting outwardly therefrom, the outer end of the other arm being pivotally coupled to said one lever.
 4. In a wire bonding machine as set forth in claim 1, wherein said knee-action means includes a pair of arms, one of the arms being rigidly secured at one end thereof to said first shaft, the other arm being pivotally mounted intermediate its ends to the outer end of said one arm, one end of the other arm being pivotally coupled to said one lever, and includinG a third shaft mounted on said support in parallelism with said first shaft for rotation relative to said support, a crank arm rigidly secured to said third shaft and disposed adjacent to said other arm, said crank arm having a lateral projection disposed to engage one side of said other arm at a location thereon adjacent to the opposite end thereof, whereby said one arm and said other arm are movable about the pivotal connection of said other arm with said one lever in response to the rotation of said third shaft in a predetermined direction.
 5. In a wire bonding machine as set forth in claim 4, wherein said other lever has means for coupling the same to said third shaft to effect rotation of the latter and thereby said crank arm in response to the rotation of the corresponding cam, each lever being biased toward the corresponding cam, each abutment being rotatably mounted on said support and having a lever engaging abutment surface spaced radially outwardly from the axis of rotation thereof, the inclination of each abutment surface being variable as a function of the rotation of the corresponding abutment relative to the support.
 6. In a wire bonding machine as set forth in claim 4, wherein said lateral projection is movable into axial alignment with said first shaft as said slide member moves into the operative position corresponding to said one cam.
 7. In a wire bonding machine as set forth in claim 4, wherein said one arm of said knee-action means projects outwardly from said first shaft toward said third shaft, said crank arm being in substantially side-by-side relationship with said other arm of said knee-action means.
 8. A wire bonding machine comprising: a support; a slide member; means mounting the slide member on the support for movement along a generally vertical path into a number of operative positions, including a home position, a first search position, an intermediate search position, and a second search position; a tool mount shiftably carried by said slide member and movable downwardly relative thereto into a bond location permitting a tool thereon to bond a wire to a workpiece when the slide member is in either of said first and second search positions; a pair of vertically spaced, parallel shafts mounted on said support for rotation relative to said support; means on the upper shaft for coupling the same to said slide member to cause movement of the latter along said path as a function of the rotation of the upper shaft; a third shaft rotatably mounted on said support and being parallel to said pair of shafts; a number of spaced cams rigidly secured to said third shaft for rotation therewith, there being a cam corresponding to each of said home, intermediate search and second search positions, respectively; a first abutment member rotatably mounted on said support adjacent to the intermediate search cam; a second abutment member rotatably mounted on the support adjacent to the second search cam, each abutment member having a generally flat abutment surface radially spaced from the axis of rotation thereof; a first lever for said intermediate search cam; means pivotally mounting one end of said first lever on the lower shaft of said pair with the opposite end of the first lever disposed to engage the intermediate search cam and the abutment surface of said first abutment; a second lever for said second search cam; knee-action means rigidly connected to the upper shaft for pivotally mounting one end of said second cam thereon, the opposite end of the second lever being disposed to engage the second search cam and the abutment surface of said second abutment member, each of said levers being biased toward the respective cam; means rigidly connected to the lower shaft for coupling the same to said knee-action means, whereby said upper shaft will rotate relative to said support when said knee-action means moves in response to movement of either of said levers, said knee-action means permitting said first lever to remain in simultaneous engagement With the second search cam and the abutment surface of the second abutment member as the slide member moves from said intermediate search to said second search position; means coupled with said tool mount for moving the same relative to said slide member into said bond location when said slide member is in either of said first and second search positions, whereby a tool carried by the tool mount will bond a wire to a workpiece below the tool; means coupled with said lower shaft for rotating the same in a direction to cause the slide member to be moved into the home position after a bond has been made with the slide member in said second search position; means movable transversely of said path for removing excess wire bonded to a workpiece when said slide member is in the home position; and means coupled with said third shaft for sequentially rotating the same relative to said support.
 9. A wire bonding machine as set forth in claim 8, wherein said knee-action means includes a pair of pivotally interconnected arms, one of the arms being rigid to said upper shaft and the other arm being pivotally coupled to the opposite end of the second lever, said means coupling the lower shaft to the knee-action means including a crank arm rigidly secured to the lower shaft and extending upwardly therefrom adjacent to said other arm of the knee-action means; said crank arm having a lateral projection engageable with the side of said other arm above the pivotal connection thereof with said one arm of the knee-action means.
 10. A wire bonding machine as set forth in claim 8, wherein the intermediate search cam and the second search cam are provided with respective cam surfaces permitting sinusoidal movements of said first and second levers, respectively.
 11. In a wire bonding machine as set forth in claim 8, wherein each of the first and second levers has a roller on the opposite end thereof, the roller of the second lever being simultaneously in engagement with the second search cam and the abutment surface of the second abutment member when the slide member is in each of said first search, intermediate search and second search positions.
 12. In a wire bonding machine as set forth in claim 11, wherein the axis of the roller of the first lever is radially spaced from the axis of rotation of the first abutment member when the slide member is in said intermediate search position, the axis of rotation of the roller of the second lever being radially spaced from the axis of rotation of the second abutment member when the slide member is in the second search position.
 13. In a wire bonding machine as set forth in claim 8, wherein said removing means includes a wire cutting torch, a wire clamp, and means for moving the torch and the clamp together along a generally horizontal path toward the tool through a distance sufficient to cause the flame of the torch to cut the wire and to permit the wire clamp to move onto the wire extension projecting upwardly from the bond of a workpiece therebelow, said wire clamp being movable toward the workpiece transversely of said horizontal path and into clipping relationship with the wire extension, whereby the wire can be separated from the bond and lifted prior to being moved along the horizontal path in reverse as the torch and the wire clamp move together away from the tool.
 14. A wire bonding machine comprising: a support; a slide member mounted on the support for movement along a generally vertical path; a tool mount shiftably mounted on the slide member and adapted to carry a wire bonding tool thereon; means coupled with said slide member for successively moving the same from a home position, to a first search position, to an intermediate search position, to a second search position, and to said home position; means coupled with the tool mount for moving the same into a bond location when the slide member is in either of said first and second search positions, whereby a tool carried by the tool mount can move a wire into bonding relationshIp to a workpiece, means for cutting the wire above a bond of the wire to the workpiece; means for gripping the excess portion of the wire projecting upwardly from the bond; means mounting the cutting means and the gripping means on said support for movement together relative to the support in a generally horizontal plane toward and away from the zone in which a wire bonded to a workpiece projects upwardly from the bond thereof, said cutting and said gripping means being movable through a distance sufficient to cause the cutting means to cut the wire and to cause the gripping means to move into gripping relationship to the wire extension projecting upwardly from the bond after the wire is cut, said gripping means being operable to pull said wire extension from the bond and to move the same away from said zone as said gripping means and said cutting means move in said plane away from said zone; and means coupled with said cutting means and said gripping means for moving the same relative to said support.
 15. A wire bonding machine as set forth in claim 14, wherein said cutting means includes a torch and said gripping means includes an actuatable wire clamp, said mounting means for the torch and the wire clamp including an arm having means thereon for shifting the wire clamp along a path transversely of the horizontal plane and along said wire extension as said arm approaches said zone, said wire clamp having means for actuating the same after it has moved a predetermined distance in one direction along said transverse path, said shifting means on said arm being operable to reverse the direction of movement of the wire clamp along said path during a portion of the movement of the arm away from said zone and as said wire clamp remains actuated, said moving means being operable to move said wire clamp and the torch in said horizontal plane away from said zone when the wire clamp has moved through said predetermined distance in the opposite direction.
 16. A wire clamp as set forth in claim 15, wherein said torch is mounted on a rod movable with said arm through a major portion of the distance of travel thereof toward said zone, and including means coupled with the rod for stopping the movement of the same after the arm has moved through said major portion of said distance, said rod having a bracket thereon projecting outwardly therefrom, said bracket having a pivot pin thereon, said wire clamp being pivotally mounted on said pivot pin, said shifting means on said arm comprising a pivot link coupled with the wire clamp for pivoting the same about said pivot pin.
 17. A wire bonding machine as set forth in claim 16, wherein said wire clamp pivots about said axis in response to the movement of said arm in said plane.
 18. A wire bonding machine as set forth in claim 14, wherein is included means coupled with said slide member for releasably securing said tool mount thereto, said tool mount moving means being operable to release the tool mount from said locking means when the slide member is in either of said search positions.
 19. A wire bonding machine as set forth in claim 18, wherein said locking means includes a first bar pivotally mounted on said slide member for movement about a first axis, a second bar pivotally mounted on the slide member for movement about a second axis, and spring means coupled with the first bar for biasing the latter against the second bar to thereby urge the second bar into engagement with said slide member, said tool mount being rigid to the second bar.
 20. A wire bonding machine as set forth in claim 19, wherein is included a second, adjustable spring for biasing the tool mount in a predetermined direction about said second axis.
 21. A wire bonding machine set forth in claim 14, wherein is included a wire drag unit carried on the support for applying a drag to the wire as it is directed toward said tool, said unit having a pair of relatively shiftable jaws, and counter weight means biasing one of the jaws toward the other jaw To apply a drag force to a wire therebetween.
 22. A wire bonding machine as set forth in claim 21, wherein is provided a rigid extension, one of the jaws of the unit being rigidly connected to the extension, and the other jaw being pivotally mounted on the extension for movement about a generally horizontal axis, said counter weight means including a rod rigid to the other jaw and extending forwardly from said extension, and a weight adjustably connected to the rod forwardly of the axis of rotation of said other jaw. 